There are numerous housing and building situations where emergency lighting may be required or desired and many systems are currently on the market for providing and controlling emergency lighting. A most common situation requiring the need for an emergency back-up lighting system relates to the failure of the normal AC power source for a building or facility. The need for emergency lighting may also arise when normal lighting is reduced or eliminated by smoke or other adverse ambient conditions, or when intruders are detected as by audible or silent alarm systems.
One common back-up or emergency lighting system utilizes AC power to illuminate one or more gas discharge lamps under normal conditions and causes one or more of such lamps to be operated from battery power when AC power fails, Both lamps may be powered from a ballast when in the AC mode, with one of the lamps being powered from the battery through an inverter in the DC mode; or one lamp may be powered from a ballast in the AC mode and the other lamp may be powered from an inverter in both modes, the inverter receiving its input from the AC source through a DC power supply in the AC mode and from the battery in the DC mode; or both lamps may be powered from inverters through DC power supplies in the AC mode, and one of the lamps from an inverter powered by a battery in the DC mode. Such a system is subject to relatively short life and operation of the battery and burn out of the inverter.
An improved emergency lighting system utilizing gas discharge lamps has been disclosed in U.S. Pat. No. 4,977,351 granted to J. P. Bavaro et al. The Bavaro et al system includes at least one gas discharge lamp, a source of AC power, means for normally operating the lamp with power from the AC source, a DC/AC inverter, and a rechargeable battery. A DC means is provided which is operative under selective emergency conditions for operating the lamp from the inverter with the inverter being powered by the battery.
Another common emergency lighting system has included a plurality of low voltage (12 volts) incandescent lamps connected in parallel to the secondary winding of a step down transformer of which the primary winding is connected to a 120 volt AC primary power source. When the primary power source fails a rechargeable back-up battery powered emergency system is interconnected via a relay switch to the lamps through circuitry which also includes the secondary winding of the step down transformer. The back-up emergency system is disconnected from the lamps via the relay switch and the battery recharged when the AC primary power source is again under normal operation. Where using the same lamps for both normal and emergency illumination, the illumination under battery power is substantially reduced unless the emergency battery source has a voltage approaching that of the voltage across the secondary winding of the step down transformer. Batteries with such low voltage ratings, and of the rechargeable type as required by the foregoing system, have a high initial cost and a relatively short life.
An improved emergency lighting system utilizing incandescent lamps has been disclosed in U.S. Pat. No. 5,149,185 granted to R. R. Mandy. A plurality of low voltage lamps (12 volts) in parallel electrical arrangement are powered from the secondary winding of a step down transformer connected to a 120 volt AC primary power source. When the primary power source is operative in normal fashion a triple pole, double throw relay switch of the emergency lighting system connects, via two of the poles, a charger to an emergency battery power source, and a third pole of the switch connects the lamps across the secondary winding of the transformer. When the primary AC power source is off, the first and second poles of the relay switch connect the emergency battery power source to selected ones of the lamps and the third pole disconnects the secondary winding from the lamps such that the only load other than system wiring across the emergency battery power source is that of the selected ones of the lamps to provide minimal emergency lighting.
It is a primary object of the present invention to provide an emergency lighting system for residential homes, apartment dwellings, office buildings and other structural facilities wherein the system includes low voltage battery powered lighting means independent of the normal AC powered lighting means.
It is a further object of the invention to provide an emergency lighting system for the one or more rooms and halls of homes, office facilities and the like wherein the system includes low voltage battery powered lighting means independent of the normal AC powered lighting means and responds automatically to AC power failure, fire, smoke detection, panic alarm actuation, unauthorized intrusion, earthquake trauma and other unexpected causes.
It is still a further object of the invention to provide an emergency lighting system for homes, apartment dwellings, office buildings and other structural facilities wherein the system includes low voltage battery powered back-up lighting means in which the battery of the system is recharged automatically via a normal AC power source when the emergency system is inactive.
It is yet another object of the invention to provide an emergency lighting system for homes, office buildings and the like which includes low voltage battery powered back-up lighting means capable of operation for extended periods of time independent of the normal AC powered lighting means of such homes and buildings, and which is activated automatically upon the occurrence of AC power failure and other unexpected emergency events and/or causes, and wherein the battery of the system is recharged automatically via a normal AC power source when the emergency system is inactive.
Other objects and advantages of the invention will be apparent from the following summary and detailed description of the emergency lighting system of the invention taken together with the accompanying drawing figures.